Elemental analysis of tissue is very useful in determining when plants are nutrient-stresses, but has less diagnostic value when concentrations are within the poorly defined sufficiency range. It has been postulated that, within the sufficiency range, there is a homeostatic, or equilibrium, level for each element. As a first approximation, we utilized the nutrient profiles of non-nutrient-limited, high-yielding wheat and potato crops during the vegetative growth phase. Plants were grown hydroponically (NFT) in NASA's Biomass Production Chamber (20 m2) using a complete nutrient solution with the electrical conductivity maintained at 0.12 S·m–1. These profiles were compared to critical deficiency levels found in the literature for both field- and controlled environment-grown plants. The homeostatic concentrations for the various nutrients were found to be 3 to 8 times that of their respective deficiency critical levels, suggesting that nutrient status can be defined even within the sufficiency range.
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